Modern telecommunication systems include heterogeneous mixtures of second, third, and fourth generation (2G, 3G, and 4G) cellular-wireless access technologies, which may be cross-compatible and may operate collectively to provide communication services. Global Systems for Mobile (GSM) is an example of 2G telecommunications technologies; Universal Mobile Telecommunications System (UMTS) is an example of 3G telecommunications technologies; and Long Term Evolution (LTE), including LTE Advanced, and Evolved High-Speed Packet Access (HSPA+) are examples of 4G telecommunications technologies.
A cellular-wireless network (e.g., may also be referred to as mobile network) includes multiple communication cells or “cells”, where an individual cell is associated with an area of coverage. A cell may be served by one or more fixed location transceivers equipped in a base station. A base station at a fixed location can be configured into multiple cells. Moreover, a cell may be associated with a portion of spectrum (e.g., a set of frequencies). Accordingly, as used herein a first cell may differ from a second cell by being associated with a different base station or by using a different portion of spectrum. Stated another way, the first cell and the differing second cell: (i) may be served by the same base station, but may use different portions of spectrum, (ii) may be served by different base stations set up in different geographic coverage areas, but may use the same portion of spectrum on the different base stations, or (iii) may be served by different base stations and may use different portions of spectrum. In some instances, differing cells may be served by the same base station, and may use the same portion of spectrum but different sector-areas.
Conventionally, the total spectrum available for cellular communication within a particular geographic coverage area is allocated, for example, by a regulatory entity (e.g., the United States Federal Communications Commission or FCC). Further, the regulatory entity may split up the total available spectrum into multiple portions of spectrum, which may also be referred to as frequency “blocks”. Consequently, a base station (or a group of base stations) that are located within the particular geographic coverage area may be allocated use of various portions of spectrum within that particular geographic coverage area. In one specific example, a regulatory entity may determine that ninety megahertz (90 MHz) may be the total amount of allocated spectrum for cellular communications (e.g., as opposed to television broadcasting or maritime communications that also use spectrum) and the regulatory entity may further determine that a size of a portion of the total available spectrum to be ten megahertz (10 MHz). The regulatory entity divides the total available spectrum into various portions so they can be auctioned off to different entities for use (e.g., commercial entities or provider of cellular service).
Because communications between a mobile user device (e.g., a user equipment or UE) and a base station use both up-link transmissions and down-link transmissions, an individual portion of spectrum (e.g., 10 MHz) assigned to one or more entities (e.g., high bidder(s) in an auction), may further be divided, in accordance with Frequency-Division Duplexing (FDD) into a first sub-portion (e.g., 5 MHz) for up-link transmissions and a second sub-portion (e.g., 5 MHz) for down-link transmissions. Accordingly, continuing the specific example from above, a base station or a group of base stations in the particular geographic coverage area may use half of the total available spectrum (e.g., 45 MHz of the 90 MHz) for up-link transmissions and the other half of the total available spectrum (e.g., 45 MHz of the 90 MHz) for down-link transmissions. Consequently, the total available spectrum may be divided into nine portions of spectrum to be auctioned off by the regulatory entity, where each portion of spectrum includes a 5 MHz frequency sub-portion for up-link transmissions and 5 MHz frequency sub-portion for down-link transmissions.
However, prior to auctioning, some of the portions of spectrum may have previously been used for a purpose other than “commercial” cellular communications, where commercial cellular communications are based on service providers providing cellular service to mobile devices of subscribing users. Stated another way, these portions of spectrum to be auctioned may have been repurposed for commercial cellular communications. In some instances, the previous entity that used the portion of spectrum before the repurposing (e.g., an “incumbent” entity) may not have completely exited the portion of spectrum, and therefore, may still be using the portion of spectrum for a short period of time or an extended period of time after it has been repurposed and allocated to a commercial cellular service provider. In instances where the incumbent entity is a protected entity (e.g., a government entity such as the United States Department of Defense), the regulatory entity may issue policies requiring that the new entity (e.g., the commercial cellular service provider) using the repurposed portion of spectrum not interfere with a “protected” use of the repurposed portion of spectrum by the incumbent entity. Accordingly, the new entity is presented with a problem of using the repurposed portion of spectrum yet avoiding interference with use of the repurposed portion of spectrum by an incumbent entity.